This invention relates to a method of controlling a search server for providing a function of searching files stored in a file storage system.
The use of computers is expanding in various industries and various usages because of improvement in performance and more inexpensive prices. In recent years, data files stored in computer systems have been increased massively. In managing such a huge number of files, there has occurred a problem that users cannot know the place storing an intended file.
To address this problem, full-text search services and metadata search services have come into use.
In a full-text search service, a search server parses file data stored in a computer system to prepare search indices. A user sends a search query to search for an intended file to the search server so that the user can access the target file based on the search results returned from the search server.
In a metadata search service, the search server extracts combinations of data composed of a metadata name and a metadata value included in each file to be searched and creates a search index of the combinations of data. A user specifies a search condition on the metadata name and the metadata value to acquire search results.
These search services will be more important for the users and will be more widely used because the file data to be stored in a computer system will increase more and more and users will have difficulty in knowing which place stores which file data for all the file data.
Traditional search servers for providing a metadata search service require to pre-register definition information defining which metadata is to be indexed for search, based on the data format for metadata search and definition information on data schema. This definition information needs to include metadata names for identifying the names of metadata and metadata types for defining possible values and data structures of metadata.
The data format for metadata search is not limited to only one kind; a metadata search may be conducted on files in different data formats. In such a case, the search server requires registration of definition information on metadata in each data format.
A known technique to manage definition information on metadata in multiple data formats is that the search server manages definition information on multiple data formats and mapping definition information for integrally managing the multiple data formats. Such a technique is disclosed in, for example, U.S. Pat. No. 7,725,454 B2. The technique according to U.S. Pat. No. 7,725,454 B2 allows metadata names in different data formats to be expressed in a unified notation. As a result, the search server can access metadata based on the unified notation, achieving indexing or searching using the unified notation.